﻿namespace homework1

{

    internal class Program

    {

        static void Main(string[] args)

        {

            Console.Write("请输入学生成绩：");

            int score = int.Parse(Console.ReadLine());

            if (score >= 90)

            {

                Console.WriteLine("成绩等级：A");

            }

            else if (score >= 60 && score <= 89)

            {

                Console.WriteLine("成绩等级：B");

            }

            else

            {

                Console.WriteLine("成绩等级：C");

            }

        }

    }

}

​